174 MICHIGAN ACADEMY OF SCIENCE. 



plates among the gastrosteges, but twelve of my thirty specimens show 

 them. They are counted as gastrosteges in my figures. As regards the 

 ])Osition of the umbilicus, Morse found the number of gastrosteges in 

 front of it to vary from 123 to 133 with an average of 128; my snakes 

 show a range of from 123 to 131 with an average of 127. If Morse has 

 counted the chin plate just referred to, then our figures are again almost 

 identical. In my snakes, the umbilicus occupies two plates, and there 

 are from fourteen to eighteen plates back of it. with an average of a 

 little over fifteen. Morse does not give particulars on this point. 



On comparing the statistics of the thirty young snakes, with those of 

 the adults studied last year, some interesting facts are brought out. 

 Just half of the thirty are males, the brood consisting of fifteen specimens 

 of each sex. In the number of gastrosteges they agree perfectly with my 

 "American Naturalist" figures, ranging from 139 to 14(3. with a mean of 

 142.3, while those published range from 138 to 148 with a mean of 142. 

 In the number of urosteges there is a similar agreement; the fifteen males 

 have from ()8 to 78 with a mean of 72.1, while the females have from 59 

 to 07 with a mean of 62.5; the mean given in the ''Naturalist" for small 

 males is 72.6 and for small females 02.6. — Turning now to the variations 

 in the number of labials and scale rows, we find that the fifteen young 

 males before us are unusually aberrant in the number of labials, while 

 the fifteen females are even more aberrant in the number of scale-rows. 

 Thus as regards the labials the two sexes vary about equally, there being 

 eleven males and ten females with the normal eight u]>per labials on both 

 sides, but only seven males and eight females with the normal ten lower 

 labials on both sides. Each sex shows sixteen aberrations from normal, 

 and all these are due to addcfJ labial ])lates. Of the thirty-two aberra- 

 tions, twenty are in the lower jaw. confirming the figures given for adults. 

 Curiously enough six of the twelve aberrations in the ui)per jaw. and ten 

 of the twenty in the lower jaw are on the right side, confii'uiing the pre- 

 viously expressed opinions that variations are as likely to occur ()n one 

 side as on the other. In number of scale-rows every male is normal, 

 having twenty-tlnec rows, while of the fifteen females only five have 

 twenty-three, four have twenty-four and six have twenty-five. Thus of 

 fifteen males, six or foi-ty per cent, were normal in both th(^ number of 

 scale-rows and of labials, while of the fifteen females only two or thirteen 

 per cent, were normal and one of those two has only two ])Ostoculars on 

 one side and is therefore abnormal. One of the abnornuil males is re- 

 markable f(n- having a supraloreal i»late on each side, the first I have seen 

 in \(itri.r. Of the twelve snakes with half plates among the gastrosteges 

 eight are females, and one of these has two such ])lates. Moreover of the 

 ten snakes with sixteen plates back of the umbilicus, six are females, and 

 the one with eighteen jtlates lliere is also a female. For all these reasons 

 I feel that the examination of these young water-snakes confirms me in 

 the opinion that the female is more variable than the male. 



